1. Field of the Invention
The present invention relates to a navigation guide device for guiding the navigation of a mobile body by providing the mobile body with information about possible events encountered along a path to be taken by the mobile body to reach a target point, a system incorporating the navigation guide device and a navigation guide method using the device and system, and a program therefor, and a medium for recording the program.
2. Description of Related Art
The conventional well-known system for guiding the movement of a mobile body such as a motor vehicle, aircraft and ship includes navigation guide systems. The navigation guide system detects the current position of a mobile body, and recognizes a target point provided by the user, and chooses an appropriate path connecting the current position with the target point. The navigation guide system displays the current position in connection with the path to be taken on a map, and provides necessary information en route at crucial points until the target point is reached.
The conventional navigation guide system incorporates a drive unit for reading map information from a recording medium such as a CD-ROM (Compact Disk-Read Only Memory) or DVD-ROM (Digital Versatile Disk-Read Only Memory). For such a navigation guide system to be installed in a limited space within a mobile body, it is necessary to make the system smaller and lighter. Furthermore, for the navigation guide system to be able to guide the mobile body smoothly to any given target point at all times, it is necessary to replace every year an old recording medium with a new recording one carrying updated map information, which may cost the user considerably.
In view of this, recently being supported by the progress of communication technology, a new navigation guide system based on wireless communication is proposed in which map information updated as appropriate by a map information provider is stored in a server system, and the user provides the server system with necessary information using a terminal installed in his/her mobile body, so that the server system can determine an appropriate path for the user""s mobile body, and transmit a radio signal carrying the information to the user""s terminal.
However, such a navigation guide system based on wireless communication has a number of problems. For example, if the mobile body is a vehicle and the vehicle passes underground or through a tunnel, communication will be interrupted, and the user will not be able to provide a server system with information regarding the vehicle""s current position, nor to receive a signal from the server system carrying information about a path to be taken by the user""s vehicle. In short, the user will be unable to receive navigation guide which would be otherwise provided by the server system. This awkward situation often occurs when the vehicle starts to move. Generally, the user wants to be informed of a path he/she should take before he/she moves his/her vehicle, and the parking place is often located underground or in a closed space within a building which may reject wireless communication. Then, the user would not be able to receive guidance from the start which would be otherwise provided by the server system. To avoid this awkward situation, the user must firstly move his/her vehicle to a nearby open space where wireless communication is possible, park the vehicle at a safe spot there, and start complicate operations necessary for being informed of an appropriate path. This will cost time and labor which will encroach on the utility of the system.
To cope with this disadvantage, it is possible to introduce a terminal which will ensure wireless communication even when the vehicle carrying the terminal is in a closed space within a building, or runs underground or through a tunnel. However, such a terminal will be generally so voluminous and complicated that practical use thereof would be difficult.
In view of above, a principal object of this invention is to provide a navigation guide device by which one can easily determine an appropriate path for reaching a target point, a system incorporating the device, and a method thereof, and a program therefor and a recording medium for recording the program.
The navigation guide device of this invention comprises current position acquisition section for acquiring information regarding the current position of a mobile body; target point acquisition section for acquiring information regarding a target point the mobile body wants to reach; information storing section for storing information regarding the current position and target point; communication state monitoring section which monitors signal transmission state under which transmission of a signal notifying the current position and target point to a path determining section should occur so that the path determining section can determine an appropriate path connecting the current position with the target point, as well as signal reception state under which reception of a signal notifying the appropriate path determined by the path determining section should occur; guide information presenting section for presenting guide information based on the received information about the appropriate path; and communication control section which, if the communication state monitoring section finds communication is impossible, causes the information storing section to store information regarding the current position and target point until communication becomes possible again and transmission of the information regarding the current position and target point is completed.
According to said aspect of this invention, the communication state monitoring section monitors signal transmission state under which transmission of a signal notifying the current position of a mobile body acquired by the current position acquisition section and a target point the mobile body wants to reach acquired by the target point acquisition section should occur, as well as signal reception state under which reception of a signal notifying a path to be taken by the mobile body determined by the path determining section based on the received information regarding the current position and target point. The communication control section instructs, if the communication state monitoring section finds communication is not possible, the information storing section to store the information regarding the current position and target point until communication becomes possible and transmission of the information regarding the current position and target point is completed. Thus, the information regarding the current position and target point is kept stored in the information storing section as long as communication is impossible, until a communicable state reappears and the guide information presenting section acquires updated information regarding a path to be taken by the mobile body. This eliminates the need for the renewed operation which will involve reentry of information regarding the current position and target point. This will lead to the improved utility of the device.
According to the navigation guide device of this invention, preferably the communication control section permits the path determining section to determine a path to be taken by a mobile body based on information regarding the current position and target point transmitted by the mobile body as long as communication is possible, and it instructs the information storing section to store the information regarding the current position and target point of the mobile body until information about the determined path is received.
According to this invention, as long as communication is possible, the path determining section is allowed to determine an appropriate path based on the received information regarding the current position of a mobile body and its target point, while the communication control section instructs the information storing section to store the information regarding the current position and target point until information about an appropriate path determined by the path determining section is received. Thus, until transmission of a signal notifying the current position of a mobile body and its target point is achieved, and reception of a signal notifying an appropriate path which the path determining section has determined based on the information regarding the current position and target point is achieved, the information regarding the current position and target point is kept stored, which will ensure the acquisition of the appropriate path by the mobile body.
According to the navigation guide device of this invention, it is preferred for the communication control section to keep, as long as communication is impossible, the device at a stand-by state to transmit a signal notifying the current position of a mobile body and its target point, and to receive a signal notifying a path to be taken by the mobile body determined by the path determining section, until the communication state monitoring section finds communication is possible.
According to this invention, the communication control section keeps the device at a stand-by state where the device is ready to transmit a signal notifying the current position of a mobile body and its target point and to receive a signal notifying a path to be taken by the mobile body determined by the path determining section, until the communication monitoring section finds communication is possible. This allows the device to be kept at a stand-by state while being relieved of actual communication until communication becomes possible, which will reduce loads involved in information handling and communication, and thus improve the information handling efficiency of the system.
According to the navigation guide device of this invention, preferably the communication control section will not put the device out of the stand-by state until it finds transmission of necessary data and reception of necessary information are completed.
According to the navigation guide device of this invention, the communication control section will put the device out of a stand-by state only after it finds transmission of necessary data and reception of necessary information are completed. Thus, even if this device is configured so as to set a path to be taken integrally, the degradation of information handling efficiency due to the accumulation of stand-by state is prevented.
According to the navigation guide device of this invention, preferably the communication state monitoring section checks at predetermined intervals whether communication is possible, and the communication control section allows communication to be restarted based on a monitoring result provided by the communication state monitoring section.
According to this invention, the communication state monitoring section checks at predetermined intervals whether communication is possible, and the communication control section allows communication to be restarted based on a monitoring result provided by the communication state monitoring section. Thus, it is not necessary for the communication state monitoring section to check at all times whether communication is possible, which will reduce a load involved in communication, and improve the efficiency of communication.
A navigation guide system of this invention comprises a navigation guide device as described above, a server system with a path determining section as described above which can communicate with the navigation guide device, and communication section enabling the navigation guide device and the server system to communicate with each other.
The present invention provides a server system with a path determining section which can communicate with a navigation guide device as described above by virtue of communication section. If the server system is connected to plural navigation guide devices, and determines an appropriate path for each of the devices, the configuration of each device will be simplified. Moreover, even if communication interrupted en route is recovered, it will be possible for each device to readily obtain information about an appropriate path without restarting operation for acquiring information regarding the current position and target point, which will lead to the enhanced utility of the system.
The navigation guide system of this invention comprises a terminal unit having current position acquisition section for acquiring information regarding the current position of a mobile body, target point acquisition section for acquiring information regarding a target point the mobile body wants to reach, information storing section for storing information regarding the current position and target point, and a terminal device with guide information presenting section for presenting guide information about a path to be taken by the mobile body determined based on the information regarding the current position and target point; a server system having a path determining section for determining a path to be taken by the mobile body based on the information regarding the current position and target point; communication section for allowing a signal notifying the current position and target point to be transmitted from the terminal unit to the path determining section of the server system, and a signal notifying the path determined by the path determining section to be transmitted from the server system to the terminal unit; communication state monitoring section for monitoring the communication state of the communication section; and a communication control section which, if the communication state monitoring section finds communication is not possible, instructs the information storing section to store the information regarding the current position and target point until communication becomes possible and transmission of the information regarding the current position and target point is completed.
According to said aspect of this invention, the communication state monitoring section monitors communication state between the terminal unit and the server system, that is, transmission of an upward signal from the terminal unit carrying information regarding the current position of a mobile body and its target point to the path determining section of the server system, as well as reception of a downward signal by the terminal unit carrying information regarding a path to be taken by the mobile body determined by the path determining section based on the information regarding the current position and target point and transmitted by the server system. The communication control section instructs the information storing section to store the information regarding the current position and target point whenever the communication state monitoring section finds communication is impossible, until a communicable state reappears and transmission of information regarding the current position and target point and reception of information regarding a path to be taken by the mobile body are completed. Thus, the information regarding the current position and target point is stored in the information storing section as long as communication is impossible, until a communicable state reappears and the guide information presenting section acquires updated information regarding a path to be taken by the mobile body, which will eliminate the need for renewed operation involving the reentry of the current position and target point which will improve the utility of the system.
According to the navigation guide system of this invention, preferably the server system comprises a memory section which can store information about an appropriate path determined by the path determining section, as long as the terminal unit cannot receive the information.
According to the present invention, the server system comprises a memory section which can store information about an appropriate path determined by the path determining section, as long as the terminal unit cannot receive the information. This permits the terminal unit to securely obtain information about an appropriate path even if communication is interrupted en route.
According to the navigation guide system of this invention, preferably the server system causes information about an appropriate path stored in its memory section to be transmitted to the terminal unit as soon as the communication state monitoring section finds communication is possible.
According to the present invention, the server system causes information about an appropriate path stored in the memory section to be transmitted to the terminal unit as soon as the communication state monitoring section finds communication is possible. This permits the terminal unit to securely obtain information about an appropriate path recently determined as soon as a communicable state reappears.
The navigation guide method of this invention for guiding, by section of calculation section, the navigation of a mobile body by providing the mobile body with necessary information at critical points along a path connecting the current position of the mobile body with its target point comprises the steps of acquiring information regarding the current position of the mobile body and its target point; transmitting the information regarding the current position and target point; monitoring the reception of a signal carrying information about a path determined based on the information regarding the current position and target point; and, if the monitoring step reveals the impossibility of communication, storing the information regarding the current position and target point in such a manner as to allow ready reading-out until a communicable state reappears and transmission of a signal notifying the current position and target point is completed.
The method comprising those steps will ensure the same advantages as will be obtained from a navigation guide device as described above.
According to the navigation guide method of this invention, the same features and advantages as will be seen in a navigation guide device as described above will be ensured because the features of the navigation guide device are also shared by the navigation guide method.
According to the navigation guide method of this invention, the same advantages as will be obtained from a navigation guide device as described above will be ensured. According to the navigation guide method, preferably information regarding the current position of a mobile body and its target point is fed via a terminal unit installed in the mobile body; a signal carrying information regarding the current position and target point is transmitted via the terminal unit to a server system, thereby permitting the server system to determine a path to be taken by the mobile body; and the terminal unit receives a signal carrying information about the path transmitted by the server system, so as to provide the user with the information about the path to be taken by the mobile body.
According to this invention, information regarding the current position of a mobile body and its target point fed via a terminal unit installed in the mobile body is transmitted to a server system so that an appropriate path to be taken by the mobile body can be determined there and a signal carrying information about an appropriate path to be taken by the mobile body to be transmitted to the terminal unit, the terminal unit thereby providing the user of the mobile body with the information about the appropriate path. Thus, the server system, even when being connected with plural terminal units, determines an appropriate path for each of the terminal units, thereby simplifying the configuration of each terminal unit. Moreover, even if communication is interrupted, and a communicable state reappears after an interval, each terminal unit can readily obtain information about an appropriate path without resorting to renewed operation for acquiring information regarding the current position and target point which would be otherwise required, which will contribute to the improved utility of the system.
The advantages mentioned above with regard to the navigation guide system will also apply to the navigation guide method of this invention, and thus the navigation guide method of this invention will have the same advantages.
A navigation guide program of this invention is so designed as to effect the navigation guide method by the use of calculation section.
According to the present invention, if the terminal unit installs a general purpose computer as calculation section, the navigation guide method can be effected by the computer which will greatly improve the utility of this invention.
A recording medium of this invention records the navigation guide program for effecting the navigation guide method of this invention in such a form as to allow the ready reading-out of the program.
According to the present invention, because the program by way of which the navigation guide method of this invention is practiced is recorded in the recording medium, handling of the navigation program becomes so easy that the utility of this invention is greatly improved.
The calculation section to effect the program of this invention recorded in a recording medium may include, to mention a few for example, a personal computer or plural computers organized into a network, or a circuit element such as a CPU represented by a principal IC of a microcomputer, a circuit board carrying plural electric components, etc.